A press feed is often used in connection with an automatic stamping press to feed coiled stock material into the press. A common method of feeding the stock material into the press is by passing it through a pair of feed rollers which apply friction to the material, and rotate in a cooperative manner to feed the stock into the press. By synchronizing the rotation of the feed rollers to the speed of the press, the stock material is fed into the press at the proper rate.
When a press is performing a punching operation, it is often desirable to align the punched holes as accurately as possible. One method of doing this uses pilot pins in the press which contact the material shortly before the press actually punches the material. The pilot pins are positioned to contact the material in a region where holes have already been punched by the press. The material is advanced to approximately the correct location by the press feeder. More precise positioning of the material then occurs as the pilot pins enter the previously punched holes, and draw them into alignment with the pilot pins. However, for this alignment to take place, the tension applied to the stock material by the feed rollers of the press feed must be removed.
The speed at which a press may operate is limited by several factors, however, including the manner in which the feed rollers are driven, the manner in which the advancement of the material by the feed rollers is synchronized to the press stroke, the manner in which the feed rollers are released from the stock material during the pilot pin alignment, and the manner in which the release of the feed rollers is synchronized to the press stroke.